41,386 research outputs found

    Comment on "Enhancing Acceleration Radiation from Ground-State Atoms via Cavity Quantum Electrodynamics"

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    This is a comment on [Phys. Rev. Lett. 91, 243004 (2003)] by Marlan O. Scully, Vitaly V. Kocharovsky, Alexey Belyanin, Edward Fry and Federico Capasso (quant-ph/0305178).Comment: 1 page, REVTeX

    The Mecoptera of Michigan

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    (excerpt) To date, no one has published on the Mecoptera of Michigan. A comprehensive taxonomic paper on the Mecoptera of Illinois, by Donald W. Webb, Illinois Natural History Survey, and Norman D. Penny, University of Kansas, is in preparation and will include keys to and descriptions of the midwestern species of Mecoptera. It is hoped that the present paper will supplement the publication by Webb and Penny and enable interested persons in Michigan to easily identify adult Mecoptera

    Patent Citations and International Knowledge Flow: The Cases of Korea and Taiwan

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    This paper examines patterns of knowledge diffusion from US and Japan to Korea and Taiwan using patent citations as an indicator of knowledge flow. We estimate a knowledge diffusion model using a data set of all patents granted in the U.S. to inventors residing in these four countries. Explicitly modeling the roles of technology proximity and knowledge decay and knowledge diffusion over time, we have found that knowledge diffusion from US and Japan to Korea and Taiwan exhibits quite different patterns. It is much more likely for Korean patents to cite Japanese patents than US patents, whereas Taiwanese inventors tend to learn evenly from both US and Japanese inventors. The frequency of a Korean patent citing a Japanese patent is almost twice that of the frequency of a Taiwanese patent citing a Japanese patent. We also find that a patent is much more likely to cite a patent from its own technological field than from another field.

    A fuzzy measure approach to motion frame analysis for scene detection

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    This paper addresses a solution to the problem of scene estimation of motion video data in the fuzzy set theoretic framework. Using fuzzy image feature extractors, a new algorithm is developed to compute the change of information in each of two successive frames to classify scenes. This classification process of raw input visual data can be used to establish structure for correlation. The algorithm attempts to fulfill the need for nonlinear, frame-accurate access to video data for applications such as video editing and visual document archival/retrieval systems in multimedia environments

    Quantum Brownian motion of multipartite systems and their entanglement dynamics

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    We solve the model of N quantum Brownian oscillators linearly coupled to an environment of quantum oscillators at finite temperature, with no extra assumptions about the structure of the system-environment coupling. Using a compact phase-space formalism, we give a rather quick and direct derivation of the master equation and its solutions for general spectral functions and arbitrary temperatures. Since our framework is intrinsically nonperturbative, we are able to analyze the entanglement dynamics of two oscillators coupled to a common scalar field in previously unexplored regimes, such as off resonance and strong coupling.Comment: 10 pages, 6 figure

    Piezoelectric pushers for active vibration control of rotating machinery

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    The active control of rotordynamic vibrations and stability by magnetic bearings and electromagnetic shakers have been discussed extensively in the literature. These devices, though effective, are usually large in volume and add significant weight to the stator. The use of piezoelectric pushers may provide similar degrees of effectiveness in light, compact packages. Tests are currently being conducted with piezoelectric pusher-based active vibration control. Results from tests performed on NASA test rigs as preliminary verification of the related theory are presented
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